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Juvenile Absence Epilepsy (JAE) – Differences from Childhood Form
Types of Seizures in Juvenile Absence Epilepsy – Absence Status Epilepticus – Triggers – Diagnosis – Genetics – Treatment – Prognosis
Juvenile Absence Epilepsy (JAE)
Juvenile Absence Epilepsy is a relatively common epilepsy syndrome.
Symptoms first appear around adolescence and persist into adulthood. Absence seizures are the first to occur. Generalized tonic-clonic seizures follow later on. Some patients have myoclonus.
Juvenile form of absence epilepsy shares similar symptoms with the childhood form but it is a distinct epilepsy syndrome with statistically less favorable prognosis of permanent remission.
Epidemiology and Genetics of JAE
Juvenile Absence Epilepsy makes up about 10% of idiopathic adult epilepsy syndromes.
Both genders appear to be affected equally. The typical age symptom onset is between 10 and 17 years with a range from 5 to 20 years.
Juvenile absence epilepsy is genetically determined but the mode of inheritance and the genes involved are not known. It is linked to chromosomes 5, 8, 18, and 21.
Symptoms of Juvenile Absence Epilepsy
In juvenile absence epilepsy absence seizures, which are episodes of transient unconsciousness, may be frequent but unlike childhood absence epilepsy they normally do not occur in hundreds per day. Absences may even be sporadic.
The level of consciousness impairment less profound than in CAE. Individual absence seizures last longer than in childhood absence epilepsy (4 to 30 seconds with an average 16 seconds).
Absence seizures are predictably provoked by hyperventilation and mental and emotional arousal.
Some patients have intractable absence seizures and may develop absence status epileptics (non-remitting, continuous absence seizure).
Generalized Tonic-Clonic Seizures
Generalized Tonic-clonic seizures (GTCS) almost invariably develop in the majority of patients 1 to 10 years after the onset of absences. GTCS may become intractable if not treated. They are typical upon awakening. The main triggers of GTCS in JAE are alcohol, fatigue, sleep deprivation, and excitement.
Myoclonus (brief muscle contractions) develops in about 20% of juvenile absence epilepsy sufferers. Myoclonic seizures are not very pronounced and they are rather sporadic. They tend to happen towards the end of the day, unlike JME in which myoclonic seizures cluster in the morning hours shortly after awakening.
Diagnosis of Juvenile Absence Epilepsy
Clinical picture of adolescent onset absence seizures, later accompanied by GTCS and possibly myoclonus makes the diagnosis.
This epileptic syndrome is most commonly confused with JME (which can have absences as the first symptom) and CAE that is unlikely to cause frequent GTCS.
EEG demonstrates normal background. Typical absence 3 to 4 Hz spike-and-wave discharges tend to vary in frequency with more spikes per wave than in CAE. The discharges tend to be more irregular than in childhood absence epilepsy.
Treatment of Juvenile Absence Epilepsy
JAE usually responds well to treatment. Seizures can be controlled in about 75% of patients.
Valproate is the drug of choice for JAE. It controls all three types of seizures: absences, GTCS, and myoclonus. Birth defects are the major concern with valproate. Liver toxicity, weight gain, hair loss, low platelets are some other major side effects.
Lamotrigine is a reasonable alternative for Juvenile Absence Epilepsy. Myoclonus is usually not the major symptom of this epilepsy syndrome, but it may be made worse by Lamotrigine. It is better tolerated than Valproate. Steven-Johnson syndrome, especially in children and in combination with Valproate, is a major concern. On the other hand, this combination may offer better seizure control.
Ethosuximide as a single drug is not an option. It has no control over GTCS and myoclonus.
Topiramate (Topamax) and Levetiracetam (Keppra) may be tried for treatment resistant seizures.
Similar to CAE, Carbamazepine, Gabapentin, Vigabatrin, and Tiagabine are contraindicated because they may lead to absence seizure status.
Prognosis in Juvenile Absence Epilepsy
Juvenile Absence Epilepsy is a lifelong epilepsy syndrome with a good response to treatment in the majority of patients. Permanent medication-free remission is not expected to occur.